In sociolinguistics a variety, also called a lect, is a specific form of a language or language cluster. This may include languages, dialects, registers, styles or other forms of language, as well as the standard variety itself.[1] The use of the word "variety" to refer to these different forms avoids the use of the term language, which many people associate only with the standard language, and the term dialect, which is often associated with non-standard varieties thought of as less prestigious or "correct" than the standard.[2] Linguists speak of both standard and non-standard varieties. "Lect" avoids the problem in ambiguous cases of deciding whether or not two varieties are distinct languages or dialects of a single language.

Variation at the level of the lexicon, such as slang and argot, is often considered in relation to particular styles or levels of formality (also called registers), but such uses are sometimes discussed as varieties themselves.[1]

Dialectology is the study of dialects and their geographic or social distribution.[3] Traditionally, dialectologists study the variety of language used within a particular speech community, a group of people who share a set of norms or conventions for language use.[1] More recently, sociolinguists have adopted the concept of the community of practice, a group of people who develop shared knowledge and shared norms of interaction, as the social group within which dialects develop and change.[5] Sociolinguists Penelope Eckert and Sally McConnell-Ginet explain, "Some communities of practice may develop more distinctive ways of speaking than others. Thus it is within communities of practice that linguistic influence may spread within and among speech communities."[6]

Although the words dialect and accent are sometimes used interchangeably in everyday English speech, linguists and scholars define the two terms differently. Accent, in technical usage, refers only to differences in pronunciation, especially those associated with geographic or social differences. Dialect, which refers to differences in syntax, morphology, and vocabulary, as well as pronunciation, is the broader term.

Most languages have a standard variety; that is, some variety that is selected and promoted by either quasi-legal authorities or other social institutions, such as schools or media. Standard varieties are more prestigious than other, nonstandard varieties and are generally thought of as "correct" by speakers of the language. Since this selection constitutes an arbitrary standard, however, standard varieties are only "correct" in the sense that they are highly valued within the society that uses the language. As Ralph Harold Fasold puts it, "The standard language may not even be the best possible constellation of linguistic features available. It is general social acceptance that gives us a workable arbitrary standard, not any inherent superiority of the characteristics it specifies."[7] Sociolinguists generally recognize the standard variety of a language as one of the dialects of that language.[8]

In some cases, an official body, such as the Académie française, describes the grammar and usage of a standard variety. More often, though, standard varieties are understood only implicitly. Writing of standard English, John Algeo suggests that the standard variety "is simply what English speakers agree to regard as good."[9]

A register (sometimes called a style) is a variety of language used in a particular social setting.[10] Settings may be defined in terms of greater or lesser formality,[11] or in terms of socially recognized events, such as baby talk, which is used in many western cultures when talking to small children, or a joking register used in teasing or playing The Dozens.[10] There are also registers associated with particular professions or interest groups; jargon refers specifically to the vocabulary associated with such registers.

Unlike dialects, which are used by particular speech communities and associated with geographical settings or social groupings, registers are associated with particular situations, purposes, or levels of formality. Dialect and register may be thought of as different dimensions of variation. For example, Trudgill suggests the following sentence as an example of a nonstandard dialect used with the technical register of physical geography:

Most speakers command a range of registers, which they use in different situations. The choice of register is affected by the setting and topic of speech, as well as the relationship that exists between the speakers.[12]

The appropriate form of language may also change during the course of a communicative event as the relationship between speakers changes, or different social facts become relevant. Speakers may shift styles as their perception of an event in progress changes. Consider the following telephone call to the Cuban Interests Section in Washington, DC.

At first, the receptionist uses a relatively formal register, as befits her professional role. After the caller identifies herself the receptionist recognizes that she is speaking to a friend, and shifts to an informal register of colloquial Cuban Spanish. This shift is similar to metaphorical code-switching, but since it involves styles or registers, is considered an example of style shifting.

An idiolect is defined as "the language use typical of an individual person."[13] An individual's idiolect may be affected by contact with various regional or social dialects, professional registers, and in the case of multilinguals, various languages.[14]

For scholars who view language from the perspective of linguistic competence, essentially the knowledge of language and grammar that exists in the mind of an individual language user, the idiolect is a way of referring to this specific knowledge. For scholars who regard language as a shared social practice, idiolect is more like a dialect with a speech community of one individual.[15]